Android and Linux re-merge into one operating system

Android and Linux re-merge into one operating system

Summary: For years, Android has been a Linux variant, but now, with the release of Linux 3.3, the two operating systems are united again.


Linux is back inside Android and Android is back inside Linux.

Linux is back inside Android and Android is back inside Linux.

Android has always been Linux, but for years the Android project went its own way and its code wasn't merged back into the main Linux tree. Now, much sooner than Linus Torvalds, Linux's founder and lead developer, had expected, Android has officially merged back into Linux's mainline.

The fork between Android and Linux all began in the fall of 2010, "Google engineer Patrick Brady stated that Android is not Linux" That was never actually the case. Android has always been Linux at heart.

At the same time though Google did take Android in a direction that wasn't compatible with the mainstream Linux kernel. As Greg Kroah-Hartman, the maintainer of the stable Linux kernel for the Linux Foundation and head of the Linux Driver Project, wrote in Android and the Linux kernel community, "The Android kernel code is more than just the few weird drivers that were in the drivers/staging/androidsubdirectory in the kernel. In order to get a working Android system, you need the new lock type they have created, as well as hooks in the core system for their security model. In order to write a driver for hardware to work on Android, you need to properly integrate into this new lock, as well as sometimes the bizarre security model. Oh, and then there's the totally-different framebuffer driver infrastructure as well." That flew like a lead balloon in Android circles.

This disagreement sprang from several sources. One was that Google's Android developers had adopted their own way to address power issues with WakeLocks. The other cause, as Google open source engineering manager Chris DiBona pointed out, was that Android's programmers were so busy working on Android device specifics that they had done a poor job of co-coordinating with the Linux kernel developers.

The upshot was that developer circles have had many heated words over what's the right way of handling Android specific code in Linux. The upshot of the dispute was that Torvalds dropped the Android drivers from the main Linux kernel in late 2009.

Despite these disagreements, there was never any danger as one claim had it in March 2011, that Android was somehow in danger of being sued by Linux because of Gnu General Public License, version 2 (GPLv2) violations. As Linus himself said at the time, claims that the Android violated the GPL were "totally bogus. We've always made it very clear that the kernel system call interfaces do not in any way result in a derived work as per the GPL, and the kernel details are exported through the kernel headers to all the normal glibc interfaces too."

Over the last few months though, as Torvalds explained last fall, that while "there's still a lot of merger to be done … eventually Android and Linux would come back to a common kernel, but it will probably not be for four to five years." Kroah-Hartman added at the time that one problem is that "Google's Android team is very small and over-subscribed to so they're resource restrained It would be cheaper in the long run for them to work with us." Torvalds then added that "We're just going different directions for a while, but in the long run the sides will come together so I'm not worried."

In the event the re-merger of the two went much faster than expected. At the 2011 Kernel Summit in Prague in late October, the Linux kernel developers "agreed that the bulk of the Android kernel code should probably be merged into the mainline." To help this process along, the Android Mainlining Project was formed.

Things continued to go along much faster then anyone had foreseen. By December, Kroah-Hartman could write, "by the 3.3 kernel release, the majority of the Android code will be merged, but more work is still left to do to better integrate the kernel and userspace portions in ways that are more palatable to the rest of the kernel community. That will take longer, but I don't foresee any major issues involved." He was right.

Today, you can compile the Android code in Linux 3.3 and it will boot. Still, as Kroah-Hartman warned, WakeLocks, still aren't in the main kernel, but even that's getting worked on. For all essential purposes, Android and Linux are back together again.

Related Stories:

Linus Torvalds on Android, the Linux fork

It's time Google starts paying for Android updates

Google open source guru says Android code will be in Linux kernel in time

Does Google's Android violate Linux's Copyright?

2011: The year of the Android OS

Topics: Mobility, Smartphones, Security, Operating Systems, Open Source, Android, Mobile OS, Linux, Hardware, Google, Software

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  • Ubuntu

    No doubt helped by Canonical's latest project that allows your Android to operate Ubuntu when plugged into a dock attached to typical PC peripherals. Which by the way is really damn cool.
  • Android and Linux re-merge into one operating system

    Great job Linus Torvalds and the devs.

  • You will be assimilated. Resistance is Futile.

    This is great news; it will also save Google a small fortune. Maintaining an up-to-date fork is a waste of effort; Google programmers can now concentrate on more interesting things.
  • Yes and no

    It seems to me that what Android is becoming is a third user interface to the Linux kernel, the others being the old fashioned CLI, and the X-Window system.

    But since Linux is just a kernel, not the whole OS, it doesn't have the split personality issues that Windows 8 seems to face (but then again, I haven't tried Windows 8 yet).
    John L. Ries
  • Android and Linux re-merge into one operating system

    And this merger will do absolutely nothing for linux, it will still suck.
    Loverock Davidson-
    • OK, even I marked that one down

      I may disagree with most of what Steven says, but that comment was uncalled for.
      • Perfectly called for

        I haven't seen a single use for linux yet that would make me use it over its competitors.
        Loverock Davidson-
    • what the hell?

      Dude, you need to take the blue pill, and chill.
      • The people need to know

        the truth about linux. If you really cared you would agree with me.
        Loverock Davidson-
      • Not from an ass_hole like you

        Now go to bed. Your mommy called you.
  • Android Fortune

    Android's growth is surprising.So wish them good luck
  • Android in mobile

    How android based mobile will take this merge as an advantages.
  • i love this zdnet rating system

    I don't have to drop my IQ to 1 and see bad trolls by loverock davidson
    • I bet you still read it anyway

      Loverock Davidson-
      • Not me

        I have yet to turn off the filter. I might for certain posters, but none of them have been rated so low.
        John L. Ries
      • "I haven't seen"

        You and your opinions are not the standard. Other people do see uses.
        - A serious Windows fan, who respects other competing technology when they are doing the right thing.
        I'll let Windows and MS defend themselves. If I or you have to defend them by saying bad things about the competition, then we have a bad OS. A good OS defends itself by people buying and using it.
      • I read it anyways

        Because I like to laugh at you. Then I down click it some more. I have yet to see more than a handful of posts from you that weren't simple flaming troll FUD. Now I can join in the fun and help assure that you won't bu up-voted back into view.
    • Subject Line

      Actually I feel it does the opposite, at least for me. Whenever I see a comment with a very low rating I actually want to read it. :-)
  • Loverock is just running scared...

    ...he's afraid that the number of Android (Linux) and IOS devices in the world will push Microsoft down to third place.
    • Cut Loverock some slack, ignore the lousy comments

      Again, most of you disagree with me on Steven, but please just mark up or down, don't clutter with replies to obvious trolling comments.

      The entire article got lost in this thread, therefore, the troll won!

      Use the rating system, mark down or up if you like, but don't respond to the troll.

      I'm not really all that pleased getting highest rated by responding to a troll, that's not my goal. Argue, sure, respond to troll, well, not really, only when necessary and I probably shouldn't have done it here.